1. Field of the Invention
This invention relates to diagnostic tests for viral diseases, and particularly diagnostic tests for AIDS.
2. Prior Art
Acquired Immume Deficiency Syndrome (AIDS) is caused by a retrovirus that is transmitted primarily by blood and blood products. In the United States the disease has occurred in certain groups more than others: homosexuals, Haitians, recipients of blood transfusions, and intravenous drug abusers. Epidemiologists now believe that the disease is more infectious and more widespread than heretofore believed.
Not all patients who are immunopositive for the AIDS virus, hereinafter HIV (Human Immunodeficiency Virus), develop any symptoms. Indeed, frequently the virus is not detected in patients who are immunopositive for HIV. The clinician therefore needs a diagnostic tool that would allow rapid determination of the prognosis of a patient who is immunopositive for HIV.
The AIDS virus has been identified and extensively characterized. Science, Volume 224, (1984) has four articles about the identification of an isolate of HIV, identified therein as HTLV-III.
The viral genome has been completedly mapped. One extensive mapping is shown in Nature, 313:277-284 (1985).
HIV is a retrovirus; that is, a virus that uses RNA as its genetic material instead of DNA and must produce a DNA equivalent of the RNA gene to replicate. Because of its unusual mode of replication, one enzyme that the virus must code for is reverse transcriptase. Reverse transcriptase is the enzyme that transcribes the genetic code from the viral RNA into viral DNA within the host cell. This is a necessary step in the replication cycle of the virus.
The reverse transcriptase for HTLV-III/LAV is described in Science, Volume 231, page 1289 (1986). Virology, volume 147, pages 326-335 (1985), characterizes reverse transcriptase and describes optimal conditions for its detection.
The reverse transcriptase for HIV usually provokes a strong immune response in healthy humans. It has now been discovered that one can make a prognosis about the future course of the disease in a given patient, who is known to be immunopositive for HIV, by detecting antibodies that inhibit the action of the reverse transcriptase. If these antibodies inhibiting the reverse transcriptase are present, the prognosis is good. However, if the individual does not have antibodies for the reverse transcriptase, the prognosis is poor. Such an individual may develop the full range of AIDS-related symtoms, which may lead to the death of the individual.